1. Field of the Invention
The present invention relates nucleotide sequences from corynebacteria coding for the pknB gene and a fermentation process for the preparation of amino acids using bacteria in which the endogenous pknB gene is amplified.
2. State of the Art
L-Amino acids, especially L-lysine, are used in human medicine, in the pharmaceutical industry, in the food industry, and, in particular, in animal nutrition. It is known that amino acids are prepared by the fermentation of strains of corynebacteria, especially Corynebacterium glutamicum. Because of their great importance, attempts are constantly being made to improve these preparative processes. Improvements to the processes may relate to measures involving the fermentation technology, e.g. stirring and oxygen supply, or the composition of the nutrient media, e.g. the sugar concentration during fermentation, or the work-up to the product form, e.g. by ion exchange chromatography, or the intrinsic productivity characteristics of the microorganism itself.
The productivity characteristics of these microorganisms are improved by using methods of mutagenesis, selection and mutant choice to give strains which are resistant to antimetabolites or auxotrophic for metabolites important in regulation, and produce amino acids.
Methods of recombinant DNA technology have also been used for some years to improve L-amino acid-producing strains of Corynebacterium by amplifying individual amino acid biosynthesis genes and studying the effect on amino acid production. However, there remains a need for improved methods of producing L-amino acids.